var _ = require('underscore');
var files = require('./files.js');
var parseStack = require('./parse-stack.js');
var fiberHelpers = require('./fiber-helpers.js');

var debugBuild = !!process.env.METEOR_DEBUG_BUILD;

// A job is something like "building package foo". It contains the set
// of messages generated by tha job. A given build run could contain
// several jobs. Each job has an (absolute) path associated with
// it. Filenames in messages within a job are to be interpreted
// relative to that path.
var Job = function (options) {
  var self = this;
  self.messages = [];

  // Should be something like "building package 'foo'"
  // Should look good in "While $title:\n[messages]"
  self.title = options.title;
  self.rootPath = options.rootPath;

  // Array of Job (jobs created inside this job)
  self.children = [];
};

_.extend(Job.prototype, {
  // options may include type ("error"), message, func, file, line,
  // column, stack (in the format returned by parseStack.parse())
  addMessage: function (options) {
    var self = this;
    self.messages.push(options);
  },

  hasMessages: function () {
    var self = this;
    return self.messages.length > 0;
  },

  // Returns a multi-line string suitable for displaying to the user
  formatMessages: function (indent) {
    var self = this;
    var out = "";
    var already = {};
    indent = new Array((indent || 0) + 1).join(' ');

    _.each(self.messages, function (message) {
      var stack = message.stack || [];

      var line = indent;
      if (message.file) {
        line+= message.file;
        if (message.line) {
          line += ":" + message.line;
          if (message.column) {
            // XXX maybe exclude unless specifically requested (eg,
            // for an automated tool that's parsing our output?)
            line += ":" + message.column;
          }
        }
        line += ": ";
      } else {
        // not sure how to display messages without a filenanme.. try this?
        line += "error: ";
      }
      // XXX line wrapping would be nice..
      line += message.message;
      if (message.func && stack.length <= 1) {
        line += " (at " + message.func + ")";
      }
      line += "\n";

      if (stack.length > 1) {
        _.each(stack, function (frame) {
          // If a nontrivial stack trace (more than just the file and line
          // we already complained about), print it.
          var where = "";
          if (frame.file) {
            where += frame.file;
            if (frame.line) {
              where += ":" + frame.line;
              if (frame.column) {
                where += ":" + frame.column;
              }
            }
          }

          if (! frame.func && ! where)
            return; // that's a pretty lame stack frame

          line += "  at ";
          if (frame.func)
            line += frame.func + " (" + where + ")\n";
          else
            line += where + "\n";
        });
        line += "\n";
      }

      // Deduplicate messages (only when exact duplicates, including stack)
      if (! (line in already)) {
        out += line;
        already[line] = true;
      }
    });

    return out;
  }

});

// A MessageSet contains a set of jobs, which in turn each contain a
// set of messages.
var MessageSet = function () {
  var self = this;
  self.jobs = [];
};

_.extend(MessageSet.prototype, {
  formatMessages: function () {
    var self = this;

    var jobsWithMessages = _.filter(self.jobs, function (job) {
      return job.hasMessages();
    });

    return _.map(jobsWithMessages, function (job) {
      var out = '';
      out += "While " + job.title + ":\n";
      out += job.formatMessages(0);
      return out;
    }).join('\n'); // blank line between jobs
  },

  hasMessages: function () {
    var self = this;
    return !! _.find(self.jobs, function (job) {
      return job.hasMessages();
    });
  },

  // Copy all of the messages in another MessageSet into this
  // MessageSet. If the other MessageSet is subsequently mutated,
  // results are undefined.
  //
  // XXX rather than this, the user should be able to create a
  // MessageSet and pass it into capture(), and functions such as
  // bundle() should take and mutate, rather than return, a
  // MessageSet.
  merge: function (messageSet) {
    var self = this;
    _.each(messageSet.jobs, function (j) {
      self.jobs.push(j);
    });
  }
});

var currentMessageSet = new fiberHelpers.EnvironmentVariable;
var currentJob = new fiberHelpers.EnvironmentVariable;
var currentNestingLevel = new fiberHelpers.EnvironmentVariable(0);

// Create a new MessageSet, run `f` with that as the current
// MessageSet for the purpose of accumulating and recovering from
// errors (see error()), and then discard the return value of `f` and
// return the MessageSet.
//
// Note that you must also create a job (with enterJob) to actually
// begin capturing errors. Alternately you may pass `options`
// (otherwise optional) and a job will be created for you based on
// `options`.
var capture = function (options, f) {
  var messageSet = new MessageSet;
  currentMessageSet.withValue(messageSet, function () {
    var job = null;
    if (typeof options === "object") {
      job = new Job(options);
      messageSet.jobs.push(job);
    } else {
      f = options; // options not actually provided
    }

    currentJob.withValue(job, function () {
      var nestingLevel = currentNestingLevel.get();
      currentNestingLevel.withValue(nestingLevel + 1, function () {
        debugBuild && console.log("START CAPTURE", nestingLevel, options.title);
        try {
          f();
        } finally {
          debugBuild && console.log("END CAPTURE", nestingLevel, options.title);
        }
      });
    });
  });
  return messageSet;
};

// Called from inside capture(), creates a new Job inside the current
// MessageSet and run `f` inside of it, so that any messages emitted
// by `f` are logged in the Job. Returns the return value of `f`. May
// be called recursively.
//
// Called not from inside capture(), does nothing (except call f).
//
// options:
// - title: a title for the job (required)
// - rootPath: the absolute path relative to which paths in messages
//   in this job should be interpreted (omit if there is no way to map
//   files that this job talks about back to files on disk)
var enterJob = function (options, f) {
  if (typeof options === "function") {
    f = options;
    options = {};
  }

  if (! currentMessageSet.get()) {
    return f();
  }

  var job = new Job(options);
  var originalJob = currentJob.get();
  originalJob && originalJob.children.push(job);
  currentMessageSet.get().jobs.push(job);

  return currentJob.withValue(job, function () {
    var nestingLevel = currentNestingLevel.get();
    return currentNestingLevel.withValue(nestingLevel + 1, function () {
      debugBuild && console.log("START", nestingLevel, options.title);
      try {
        return f();
      } finally {
        debugBuild && console.log("DONE", nestingLevel, options.title);
      }
    });
  });
};

// If not inside a job, return false. Otherwise, return true if any
// messages (presumably errors) have been recorded for this job
// (including subjobs created inside this job), else false.
var jobHasMessages = function () {
  var search = function (job) {
    if (job.hasMessages())
      return true;
    return !! _.find(job.children, search);
  };

  return currentJob.get() ? search(currentJob.get()) : false;
};

// Given a function f, return a "marked" version of f. The mark
// indicates that stack traces should stop just above f. So if you
// mark a user-supplied callback function before calling it, you'll be
// able to show the user just the "user portion" of the stack trace
// (the part inside their own code, and not all of the innards of the
// code that called it).
var markBoundary = function (f) {
  return parseStack.markBottom(f);
};

// Record a build error. If inside a job, add the error to the current
// job and return (caller should do its best to recover and
// continue). Otherwise, throws an exception based on the error.
//
// options may include
// - file: the file containing the error, relative to the root of the build
//   (this must be agreed upon out of band)
// - line: the (1-indexed) line in the file that contains the error
// - column: the (1-indexed) column in that line where the error begins
// - func: the function containing the code that triggered the error
// - useMyCaller: true to capture information the caller (function
//   name, file, and line). It captures not the information of the
//   caller of error(), but that caller's caller. It saves them in
//   'file', 'line', and 'column' (overwriting any values passed in
//   for those). It also captures the user portion of the stack,
//   starting at and including the caller's caller.
//   If this is a number instead of 'true', skips that many stack frames.
// - downcase: if true, the first character of `message` will be
//   converted to lower case.
// - secondary: ignore this error if there are are already other
//   errors in this job (the implication is that it's probably
//   downstream of the other error, ie, a consequence of our attempt
//   to continue past other errors)
var error = function (message, options) {
  options = options || {};

  if (options.downcase)
    message = message.slice(0,1).toLowerCase() + message.slice(1);

  if (! currentJob.get())
    throw new Error("Error: " + message);

  if (options.secondary && jobHasMessages())
    return; // skip it

  var info = _.extend({
    message: message
  }, options);

  if ('useMyCaller' in info) {
    if (info.useMyCaller) {
      info.stack = parseStack.parse(new Error()).slice(2);
      var howManyToSkip = (
        typeof info.useMyCaller === "number" ? info.useMyCaller : 0);
      var caller = info.stack[howManyToSkip];
      info.func = caller.func;
      info.file = caller.file;
      info.line = caller.line;
      info.column = caller.column;
    }
    delete info.useMyCaller;
  }

  currentJob.get().addMessage(info);
};

// Record an exception. The message as well as any file and line
// information be read directly out of the exception. If not in a job,
// throws the exception instead. Also capture the user portion of the stack.
//
// There is special handling for files.FancySyntaxError exceptions. We
// will grab the file and location information where the syntax error
// actually occurred, rather than the place where the exception was
// thrown.
var exception = function (error) {
  if (! currentJob.get()) {
    // XXX this may be the wrong place to do this, but it makes syntax errors in
    // files loaded via unipackage.load have context.
    if (error instanceof files.FancySyntaxError) {
      error = new Error("Syntax error: " + error.message + " at " +
        error.file + ":" + error.line + ":" + error.column);
    }
    throw error;
  }

  var message = error.message;

  if (error instanceof files.FancySyntaxError) {
    // No stack, because FancySyntaxError isn't a real Error and has no stack
    // property!
    currentJob.get().addMessage({
      message: message,
      file: error.file,
      line: error.line,
      column: error.column
    });
  } else {
    var stack = parseStack.parse(error);
    var locus = stack[0];
    currentJob.get().addMessage({
      message: message,
      stack: stack,
      func: locus.func,
      file: locus.file,
      line: locus.line,
      column: locus.column
    });
  }
};

var assertInJob = function () {
  if (! currentJob.get())
    throw new Error("Expected to be in a buildmessage job");
};

var assertInCapture = function () {
  if (! currentMessageSet.get())
    throw new Error("Expected to be in a buildmessage capture");
};

var buildmessage = exports;
_.extend(exports, {
  capture: capture,
  enterJob: enterJob,
  markBoundary: markBoundary,
  error: error,
  exception: exception,
  jobHasMessages: jobHasMessages,
  assertInJob: assertInJob,
  assertInCapture: assertInCapture
});